The Applicant has worked extensively with some of the foulest waters imaginable. In many such instances the treatment of such fluids can be extremely expensive. For example, the global direct costs to oil companies for treating water used in oil and gas recovery surpassed $20 billion in 2007, with expenses skyrocketing in the following years.
While the instant invention can be used on most any fluid that is contaminated, it is especially suited for water contaminated with aerobic or anaerobic bacteria, or waters that benefit from the reduction in dissolved or suspended solids or conditioning thereof. Aerobic bacteria, often called a slime forming bacteria, produces a polysaccharide bio-film that often adheres to the shale and inhibits the flow of gasses. Anaerobic bacteria can be include an acid producing bacteria such as APB that grows on metal and secretes acid producing corrosion, or SRB which is a sulfate reducing bacteria that produces hydrogen sulfide and has the potential to create a dangerous situation and literally shut down a well.
The produced water example will highlight a major problem with contaminated water, which is produced waters are the byproduct associated with oil and gas production and contain both natural and manmade contaminants. The US Department of Energy (DOE) has called produced water “by far the largest single volume byproduct or waste stream associated with oil and gas production.” The DOE further terms its treatment a serious environmental concern and a significantly growing expense to oil and gas producers. While the instant cavitation reactor has a beneficial use with most any water treatment problem, the produced water problem highlights the effectiveness of the system.
In 2007, the world's oil and gas fields produced 80 billion barrels of water needing processing. The average is now almost nine barrels of produced water for each barrel of oil extracted. And the ratio of water to hydrocarbons increases over time as wells become older. That means less oil or gas and more contaminated water as we attempt to meet rising global energy needs.
The discharge of produced water is unacceptable unless treated. Currently it is necessary to introduce chemical polymers to flocculate the slurry and further treat the volatile organic compounds (VOC's) which are emitted as gases from certain solids or liquids. The VOC's are known to include a variety of chemicals some of which may have short or long term adverse health effects and is considered an unacceptable environmental discharge contaminant. Unfortunately, the use of polymers and a settling time is so expensive that economically it becomes more conducive to treat the waste off-site which further adds to the cost of production by requiring off-site transport/treatment or shipped to a hazardous waste facility where no treatment is performed.
The applicants have developed an enhanced fluid treatment system which employs the use of a cavitation reactor. The instant invention advances the developed processes of oxidizing heavy metals, converting oil sheens to inert CO2 and water, precipitating certain cations or conditioning thereof, and oxidizing organics at a well site. Further, the system may treat numerous other fluid related problems providing both an economic and environmental benefit.
There are many gas fields, most notably in North America, that contain enormous amounts of natural gas. This gas is trapped in shale formations that require stimulating the well using a process known as fracturing or fracing. The fracing process uses large amounts of water and large amounts of particulate fracing material (frac sands) to enable extraction of the gas from the shale formations. After the well site has been stimulated, the water pumped into the well during the fracing process is removed, referred to as flowback fluid or frac water.
Water is an important natural resource that needs to be conserved wherever possible. One way to conserve water is to clean and recycle this flowback or frac water. The recycling of frac water has the added benefit of reducing waste product, namely the flowback fluid, which will need to be properly disposed. On site processing equipment, at the well, is the most cost effective and environmentally friendly way of recycling this natural resource.
It takes from 1 million to 4.5 million gallons of fresh water to fracture a horizontal well. This water may be untreated water available from local streams, ponds, wells or may be treated water purchased from a municipal water utility. Water is typically trucked to the well site by tanker trucks, which carry roughly five thousand gallons per trip. For instance, if approximately 300 five thousand gallon tanker trucks are used to carry away more than one million gallons of flowback water per well, the amount of fuel consumed in addition to the loss of water is unacceptable. For a 3 well frac site these numbers will increase by a factor of three.
The present invention provides a cost-effective onsite cavitation reactor that combines ozone, hydrodynamic cavitation, acoustic cavitation and electro-precipitation for enhanced water treatment. The treatment apparatus is sized and configured to optimize the amount of water to be processed. The treatment system is compact, transportable and self-contained, including both the processing equipment and the power supply to the run the system. It is also configured to be compact in overall size to facilitate its use a remote well sites. The treatment device is also readily transportable such that it can be moved from well site to well site.